/* =====================================================================
   Algorithm Forge — design system
   One stylesheet shared by the hub, every simulation, and the Arena.
   Tokens first, then layout primitives, then components.
   ===================================================================== */
@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;500;700&display=swap");

:root {
  /* surfaces */
  --bg: #0d1117;
  --bg-2: #121823;
  --panel: #161d2a;
  --panel-2: #1c2536;
  --line: #2a3448;
  --line-2: #36425b;
  /* text */
  --ink: #e8edf5;
  --ink-2: #b4bfd1;
  --muted: #7f8ba3;
  /* brand: ember + steel */
  --ember: #ff8a3d;
  --ember-2: #ffb07a;
  --ember-soft: rgba(255, 138, 61, 0.14);
  --steel: #5ab0ff;
  --steel-soft: rgba(90, 176, 255, 0.14);
  /* semantic states used by EVERY visualization (keep consistent!) */
  --c-compare: #ffd24d;   /* being compared            */
  --c-swap: #ff5d73;      /* being swapped / written   */
  --c-done: #3ddc97;      /* in final position / found */
  --c-active: #5ab0ff;    /* current / pivot / focus   */
  --c-pivot: #c38bff;     /* pivot / special           */
  --c-dim: #3a4458;       /* excluded / out of range   */
  --c-bar: #6b7fa6;       /* default element           */
  --ok: #3ddc97;
  --bad: #ff5d73;
  --warn: #ffd24d;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --font: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  color-scheme: dark;
}

:root[data-theme="light"] {
  --bg: #f6f7fb;
  --bg-2: #eef1f7;
  --panel: #ffffff;
  --panel-2: #f3f5fa;
  --line: #d9dfeb;
  --line-2: #c6cedf;
  --ink: #141a26;
  --ink-2: #3b4658;
  --muted: #6a7589;
  --ember: #e0661a;
  --ember-2: #b8510f;
  --ember-soft: rgba(224, 102, 26, 0.12);
  --steel: #1f6fd1;
  --steel-soft: rgba(31, 111, 209, 0.1);
  --c-compare: #e0a800;
  --c-swap: #e23a55;
  --c-done: #12a26b;
  --c-active: #1f6fd1;
  --c-pivot: #8a4fd6;
  --c-dim: #cfd6e4;
  --c-bar: #8fa0c2;
  --ok: #12a26b;
  --bad: #e23a55;
  --warn: #c98f00;
  --shadow: 0 10px 30px rgba(20, 30, 60, 0.12);
  color-scheme: light;
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #f6f7fb; --bg-2: #eef1f7; --panel: #ffffff; --panel-2: #f3f5fa;
    --line: #d9dfeb; --line-2: #c6cedf; --ink: #141a26; --ink-2: #3b4658; --muted: #6a7589;
    --ember: #e0661a; --ember-2: #b8510f; --ember-soft: rgba(224,102,26,.12);
    --steel: #1f6fd1; --steel-soft: rgba(31,111,209,.1);
    --c-compare: #e0a800; --c-swap: #e23a55; --c-done: #12a26b; --c-active: #1f6fd1;
    --c-pivot: #8a4fd6; --c-dim: #cfd6e4; --c-bar: #8fa0c2;
    --ok: #12a26b; --bad: #e23a55; --warn: #c98f00;
    --shadow: 0 10px 30px rgba(20,30,60,.12);
    color-scheme: light;
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 15px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--steel); text-decoration: none; }
a:hover { text-decoration: underline; }
code, kbd, pre, .mono { font-family: var(--mono); }
code { background: var(--panel-2); border: 1px solid var(--line); border-radius: 5px; padding: 0 5px; font-size: 0.9em; }
kbd { background: var(--panel-2); border: 1px solid var(--line-2); border-bottom-width: 2px; border-radius: 5px; padding: 0 6px; font-size: 0.82em; }
h1, h2, h3, h4 { line-height: 1.2; margin: 0 0 0.5em; letter-spacing: -0.01em; }
h1 { font-size: clamp(1.6rem, 3vw, 2.3rem); font-weight: 800; }
h2 { font-size: 1.35rem; font-weight: 700; }
h3 { font-size: 1.05rem; font-weight: 700; }
p { margin: 0 0 0.8em; }
hr { border: 0; border-top: 1px solid var(--line); margin: 1.5rem 0; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 14px;
  padding: 10px 20px;
  background: var(--bg); /* fallback for browsers without color-mix */
  background: color-mix(in srgb, var(--bg) 97%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; color: var(--ink); letter-spacing: -0.02em; }
.brand:hover { text-decoration: none; }
.brand .logo { width: 28px; height: 28px; }
.brand small { font-weight: 600; color: var(--muted); font-size: 0.78rem; }
.topbar nav { display: flex; gap: 4px; margin-left: 8px; flex-wrap: wrap; }
.topbar nav a { color: var(--ink-2); padding: 6px 10px; border-radius: 8px; font-weight: 600; font-size: 0.9rem; }
.topbar nav a:hover, .topbar nav a.active { background: var(--panel-2); color: var(--ink); text-decoration: none; }
.topbar .spacer { flex: 1; }
.topbar .menu-btn { display: none; }

/* ---------- layout ---------- */
.wrap { max-width: 1280px; margin: 0 auto; padding: 24px 20px 64px; }
.wrap.narrow { max-width: 900px; }
.grid { display: grid; gap: 16px; }
.grid.cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid.cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.sim-layout { display: grid; grid-template-columns: minmax(0, 1fr) 360px; gap: 16px; align-items: start; }
.sim-layout > *, .grid > * { min-width: 0; }
@media (max-width: 980px) {
  .sim-layout { grid-template-columns: minmax(0, 1fr); }
  .grid.cols-3, .grid.cols-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 640px) {
  .grid.cols-2, .grid.cols-3, .grid.cols-4 { grid-template-columns: 1fr; }
  .wrap { padding: 16px 16px 48px; }
  .topbar { padding: 10px 16px; }
  .topbar { flex-wrap: wrap; }
  .topbar nav { display: none; order: 10; width: 100%; margin: 8px 0 0; flex-direction: column; gap: 2px; }
  .topbar.nav-open nav { display: flex; }
  .topbar nav a { padding: 10px 12px; }
  .topbar .menu-btn { display: inline-flex; }
  .topbar .chip { display: none; }
  .player .scrub { min-width: 100px; }
}
.stack > * + * { margin-top: 16px; }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }

/* ---------- panels / cards ---------- */
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
}
.panel.flush { padding: 0; overflow: hidden; }
.panel-title {
  display: flex; align-items: center; gap: 8px;
  font-size: 0.78rem; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--muted); margin-bottom: 10px;
}
.card {
  display: block; background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px; color: var(--ink); transition: transform .15s ease, border-color .15s ease, box-shadow .15s ease;
}
a.card:hover { transform: translateY(-2px); border-color: var(--ember); box-shadow: var(--shadow); text-decoration: none; }
.card h3 { margin-bottom: 4px; }
.card p { color: var(--ink-2); font-size: 0.92rem; margin: 0; }
.eyebrow { font-size: 0.72rem; font-weight: 800; letter-spacing: 0.12em; text-transform: uppercase; color: var(--ember); }

/* ---------- chips / badges ---------- */
.chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 2px 9px; border-radius: 999px; font-size: 0.75rem; font-weight: 700;
  background: var(--panel-2); border: 1px solid var(--line); color: var(--ink-2);
}
.chip.ember { background: var(--ember-soft); color: var(--ember); border-color: transparent; }
.chip.steel { background: var(--steel-soft); color: var(--steel); border-color: transparent; }
.chip.ok { background: color-mix(in srgb, var(--ok) 16%, transparent); color: var(--ok); border-color: transparent; }
.chip.bad { background: color-mix(in srgb, var(--bad) 16%, transparent); color: var(--bad); border-color: transparent; }
.chip.warn { background: color-mix(in srgb, var(--warn) 18%, transparent); color: var(--warn); border-color: transparent; }
.lvl { font-family: var(--mono); font-weight: 700; }
.lvl-0 { color: #3ddc97; } .lvl-1 { color: #7bd88f; } .lvl-2 { color: #5ab0ff; }
.lvl-3 { color: #c38bff; } .lvl-4 { color: #ff8a3d; } .lvl-5 { color: #ff5d73; }
.lvl-6 { color: #ffd24d; } .lvl-7 { color: #4de1ff; }

/* ---------- buttons & inputs ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 7px 13px; border-radius: 9px; border: 1px solid var(--line-2);
  background: var(--panel-2); color: var(--ink); font: 600 0.88rem var(--font);
  cursor: pointer; user-select: none; transition: background .12s, border-color .12s, transform .05s;
}
.btn:hover { border-color: var(--ember); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn.primary { background: var(--ember); border-color: var(--ember); color: #1b0f05; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.steel { background: var(--steel); border-color: var(--steel); color: #04121f; }
.btn.ghost { background: transparent; }
.btn.icon { padding: 7px 10px; min-width: 38px; }
.btn.sm { padding: 4px 9px; font-size: 0.8rem; }
input[type="text"], input[type="number"], select, textarea {
  background: var(--bg-2); color: var(--ink); border: 1px solid var(--line-2); border-radius: 8px;
  padding: 6px 10px; font: 500 0.9rem var(--font);
}
input[type="range"] { accent-color: var(--ember); }
label.field { display: flex; flex-direction: column; gap: 4px; font-size: 0.8rem; color: var(--muted); font-weight: 600; }

/* ---------- player controls ---------- */
.player { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.player .scrub { flex: 1; min-width: 140px; }
.player .step-label { font-family: var(--mono); font-size: 0.8rem; color: var(--muted); min-width: 90px; text-align: right; }

/* ---------- code panel (pseudocode with live line highlight) ---------- */
.code {
  font-family: var(--mono); font-size: 0.83rem; line-height: 1.65;
  background: var(--bg-2); border: 1px solid var(--line); border-radius: var(--radius-sm);
  padding: 8px 0; overflow-x: auto; counter-reset: ln;
}
.code .ln { display: block; padding: 0 12px 0 44px; position: relative; white-space: pre; border-left: 3px solid transparent; }
.code .ln::before { counter-increment: ln; content: counter(ln); position: absolute; left: 8px; width: 26px; text-align: right; color: var(--muted); opacity: .6; }
.code .ln.hl { background: var(--ember-soft); border-left-color: var(--ember); }
.code .kw { color: var(--steel); font-weight: 700; }
.code .cm { color: var(--muted); font-style: italic; }
.code .nm { color: var(--ember-2); }

/* ---------- counters ---------- */
.counters { display: grid; grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); gap: 8px; }
.counter { background: var(--bg-2); border: 1px solid var(--line); border-radius: 10px; padding: 8px 10px; }
.counter .k { font-size: 0.7rem; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); font-weight: 700; }
.counter .v { font-family: var(--mono); font-size: 1.25rem; font-weight: 700; }

/* ---------- narration ---------- */
.narrate {
  background: var(--steel-soft); border: 1px solid color-mix(in srgb, var(--steel) 35%, transparent);
  border-radius: 10px; padding: 10px 12px; min-height: 48px; font-size: 0.92rem;
}
.narrate b { color: var(--ink); }

/* ---------- stage (svg canvas for visualizations) ---------- */
.stage { width: 100%; background: var(--bg-2); border: 1px solid var(--line); border-radius: var(--radius); display: block; }
.stage text { font-family: var(--mono); }
.stage text:not([fill]) { fill: var(--ink); }
.legend { display: flex; flex-wrap: wrap; gap: 12px; font-size: 0.78rem; color: var(--ink-2); }
.legend i { display: inline-block; width: 12px; height: 12px; border-radius: 3px; margin-right: 5px; vertical-align: -1px; }

/* ---------- tables (DP tables, traces) ---------- */
table.t { border-collapse: collapse; font-family: var(--mono); font-size: 0.82rem; }
table.t th, table.t td { border: 1px solid var(--line); padding: 4px 8px; text-align: center; min-width: 34px; }
table.t th { background: var(--panel-2); color: var(--ink-2); font-weight: 700; }
table.t td.hl { background: var(--ember-soft); outline: 2px solid var(--ember); outline-offset: -2px; }
table.t td.src { background: var(--steel-soft); }
table.t td.done { color: var(--c-done); font-weight: 700; }
.scroll-x { overflow-x: auto; }

/* ---------- tabs ---------- */
.tabs { display: flex; gap: 2px; border-bottom: 1px solid var(--line); margin-bottom: 12px; flex-wrap: wrap; }
.tabs button { background: none; border: 0; color: var(--muted); font: 700 0.85rem var(--font); padding: 8px 12px; cursor: pointer; border-bottom: 2px solid transparent; }
.tabs button.on { color: var(--ink); border-bottom-color: var(--ember); }

/* ---------- callouts ---------- */
.callout { border-left: 3px solid var(--ember); background: var(--ember-soft); padding: 10px 14px; border-radius: 0 10px 10px 0; }
.callout.steel { border-color: var(--steel); background: var(--steel-soft); }
.callout.ok { border-color: var(--ok); background: color-mix(in srgb, var(--ok) 12%, transparent); }
.callout.bad { border-color: var(--bad); background: color-mix(in srgb, var(--bad) 12%, transparent); }

/* ---------- hero ---------- */
.hero { padding: 36px 0 12px; }
.hero p.lead { font-size: 1.1rem; color: var(--ink-2); max-width: 760px; }

footer.foot { border-top: 1px solid var(--line); color: var(--muted); font-size: 0.82rem; padding: 18px 20px; text-align: center; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.muted { color: var(--muted); }
.small { font-size: 0.85rem; }

/* utilities shared by every page */
[hidden] { display: none !important; }
select { max-width: 100%; }